Merge branch...

Merge branch '294-parallelcyclotrontracker-crashes-in-single-particle-mode-when-all-particles-are-lost' into 'master'

Resolve "ParallelCyclotronTracker crashes (in single particle?) mode when all particles are lost"

Closes #294

See merge request OPAL/src!69

src/Algorithms/ParallelCyclotronTracker.cpp

@@ -2222,6 +2222,10 @@ bool ParallelCyclotronTracker::deleteParticle(){
               << "on stripper, collimator, septum, or out of cyclotron aperture"
               << endl;
 
+        if (totalnum == 0) {
+            return flagNeedUpdate;
+        }
+
         Vector_t const meanR = calcMeanR();
         Vector_t const meanP = calcMeanP();